An Efficiency Boost for Fragment Screening, Kinetics and Affinity Measurements by Spr Spectroscopy

Surface plasmon resonance (SPR) spectroscopy is now even better suited to measure biomolecular interactions. Pall's Pioneer platform with its OneStep^® gradient injections significantly increases the efficiency of the analysis process over traditional SPR spectroscopy by determining binding kinetics and affinity parameters in a single step. For fragment screening, the Pioneer FE system is the only available SPR system that enables single-injection fragment binding competition assays.

Pall's Pioneer platform comprises instruments for high-quality surface plasmon resonance spectroscopy. These enable label-free measurement of biomolecular interactions in real-time.
Extending measurement to include molecules smaller than 150 daltons, the Pioneer systems are ideally suited for fragment analysis and studies on protein aggregation.

The ground-breaking OneStep gradient injections

OneStep injections on the Pioneer platform use Taylor dispersion to generate an analyte concentration gradient that provides a high-resolution dose response in a single injection — allowing full analyte titration over 3 to 4 orders of magnitude in concentration within a few minutes. OneStep can also be used to determine the analyte diffusion coefficient and assess whether the analyte is heterogeneous or aggregated.

Key features of the Pioneer system for binding kinetics and affinity:

• 3 channel, fully automated SPR system
• OneStep gradient injections acquire full kinetics titration automatically and within minutes, eliminating the time and error associated with making dilutions
• Exquisite sensitivity and minimal noise for high affinity binding pairs
• Up to 72 hours of unattended run time
• Integrated, proven data analysis software based on Scrubber and CLAMP platforms
• Kretschmann optics for high sensitivity and stability

Fragment screening using the Pioneer FE system

Pall’s Pioneer FE system enables SPR-based screening for identification of fragment candidates. Fragment screening is challenging with a large numbers of samples to process, low molecular weight analytes (<300 Da), and weak affinity interactions (K_D: 10 µM to 10 mM). This combination of challenges makes it impractical to test binding above the K_D and frequently results in making decisions based on small, square-shaped response curves.

OneStep eliminates this by generating a continuous concentration gradient using the sample and running buffer. Weak affinity binding associated with fragments can be fitted with a real-time equilibrium isotherm model, since off-rates are fast enough to make the steady-state approximation.

OneStep injections are not only suitable for direct assays, but also for competitive analyses. Competition assays are very useful in drug discovery, yielding the ability to find active site binders directly by competing fragment hits with a control molecule. Two sample components can be injected over the biosensor surface to perform a full kinetic analysis with site-specific competition using Pall’s NeXtStep Injection technology.

Key features of the Pioneer system for fragment screening:

• Make decisions early on with reliable affinity (K_D) and kinetic (k_d, k_a) data directly from the primary screen
• High throughput: up to 768 samples in 24 hours in a single experiment
• The only SPR instrument to perform fragment binding competition assays in a single injection
• Normalize screening data across different sensor chips, days, users or instruments to compare an entire screen campaign and select actives from the global data set